End user experience or Quality of Experience (QoE) is a differentiator for mobile operators and internet service providers. Applications are increasingly attempting to adapt to ensure a good QoE. For example, Adaptive Bit Rate video adapts the required throughput by changing media rate by using an encoded video format with a suitable bitrate. Currently this is done by trying to estimate the throughput between the service provider server and the application (app) in the client (e.g. in a User Equipment, UE), e.g. based on measured link bit rate or round trip time (RTT). How frequently the bitrate can be changed varies. A typical interval for adaptive video streaming would be every 2-5 seconds.
Feedback of available throughput from Radio Access Network (RAN) nodes to nodes outside of the RAN is being discussed (e.g. in Third Generation Partnership Project (3GPP), Institute of Electrical and Electronics Engineers (IEEE), and Internet Engineering Task Force (IETF) proposals) to improve end user QoE.
In the IETF informal internet draft, “Requirements and reference architecture for Mobile Throughput Guidance Exposure” by A. Jain et al. 19 Feb. 2015, a throughput guidance is sent from the mobile network to a Transmission Control Protocol (TCP) server. The idea is to have a Throughput guidance provider residing in the RAN, which feeds the TCP server periodically with estimated throughput in downlink per UE or per flow. Regarding the accuracy of the throughput guidance it is stated that the throughput guidance should be treated only as an estimate to the optimization algorithm running at the TCP server. The TCP server that receives this information should not assume that it is always accurate and up to date. Specifically, the TCP server should check the validity of the information received and if it finds it erroneous it should discard it and possibly take other corrective actions (e.g., discard all future throughput guidance information from a particular Internet Protocol (IP) prefix).